Polymer composition with high flexibility and flame retardancy

ABSTRACT

The invention relates to polymer compositions used for preparing conjunction devices. The conjunction devices comprise one or more elements including a static/moving current medium or communication medium; and a halogen-free polymer composition surrounding the element(s). The polymer composition includes a linear very low density polyethylene (VLDPE) composition and one or more polyolefin-elastomers. In addition, the polymer composition includes a flame retardant filler.

The invention relates to polymer compositions as defined in the claims,suitable for preparing conjunction devices. Conjunction devices whichare halogen-free but have flame retardance properties are used invarious applications such as in applications in the vicinity ofinflammable goods or in applications where high safety standards have tobe met.

The challenges in the development of conjunction devices are related tothe various industrial requirements which have to be met. Theseindustrial requirements concern flame retardance properties, sheathing(mechanical protection), elongation at break, strength at break,flexibility, stripping force, low friction, and resistance to scratches.In order to improve one or the other property, an infinite number ofpolymer materials and polymer additives are available. However, while itmay be possible to improve one or the other parameter by routinedevelopment, changing the polymer composition in this course results inthe deterioration of at least one other parameter. Since it is notpredictable how the above parameters will vary, if the polymercomposition is changed, many approaches have been tried to fulfill theindustrial requirements for conjunction devices.

BACKGROUND PRIOR ART

EP1102282 A1 discloses devices surrounded by an inner and an outerlayer. The outer layer provides chemical resistance and abrasivity([0011]) and the inner layer provides flame retardancy and highelongation and tensile strength ([0011]). One example of an inner layeris Rezeptur 7 in Table 1 of page 6. The layers are described asproviding a high elongation. In order to provide a desired adhesivenessbetween the layers, the layers can comprise block copolymers. However,as shown in Example 2 herein, block copolymers do not provide thehighest elongation at break. Furthermore, EP1102282 A1 does not teachthe relevance of the type of polyolefines regarding the elongationproperties.

Compositions comprising polyolefin elastomers (POE) in combination witha high density polyethylene (HDPE) and a polyethylene having a densityof below 0.910 g/cm³ as well as a flame retardant, a coupling agent, anda stabilizer are known in the art. Using a combination of HDPE and VLDPE(very low density polyethylene) is known for achieving good elongationproperties. However, the use of HDPE is neither required nor desirablein the context of the present invention.

Other known polymer compositions may provide an elongation of only up toabout 300%. Such compositions may include an ultra-high molecular weightpolysiloxane.

DE3633056 A1 teaches that VLDPEs increase the resistance to thermaldistortion (claim 5). It neither discloses nor suggests using acombination of the particular VLDPE and particular polyolefin-elastomerof the present invention for providing a polymer composition having ahigh content of flame retardant filler.

WO 2010015876 A1, WO 2013030795 A1, and WO 2007032573 A1 disclosecompositions which have an elongation at break below only 200%.

WO 2002026879 A1 discloses a halogen-free polymeric compositionincluding: (a) at least two metallocene catalysed olefin polymers and/orcopolymers wherein at least one of the olefin polymers and/or copolymersis elastomeric; and (b) an effective amount of at least one filler whichis capable of providing the polymeric composition with flame retardantproperties substantially similar to that of plasticised PVC (see claim1). The composition includes at least about 30 PHR of at least onemetallocene catalysed polyolefin elastomer (POE). For more flexiblecompositions, even higher POE contents are suggested. The presentinvention does not require such high POE contents in order to providethe desired elongation properties.

WO 2008014597 A1 and WO 2010024602 A2 disclose compositions having anelongation of up to about 800%. However, these compositions do notcontain high levels of fillers which are flame retardants.

It is therefore an object of the present invention to provide polymercompositions which can be used for preparing conjunction devices havinggood long term mechanical stability and flame retardancy, in particularlow flammability, good resistance to pressure at high temperatures(mechanical protection), high elongation at break, good dimensionalstability, high strength at break, and high flexibility. Otherproperties which may be good relate to the waviness (which is related tothe intensity of the spiral appearance of a cable surface predefined bythe twisted cores), stripping force for removal of the polymercomposition from the elements, low friction, and resistance toscratches.

SUMMARY OF THE INVENTION

The invention relates to a polymer composition or compound comprising atleast the following components:

-   -   (a) 24-32 wt.-% of a linear very low density polyethylene        (VLDPE) composition having a density in the range from 0.85        g/cm³ to 0.95 g/cm³, as measured according to ISO 1183;    -   (b) 10-17 wt.-% of a polyolefin-elastomer, which is an ultra-low        density random ethylene-octene copolymer having    -   a glass transition temperature of −50° C., and/or    -   a melting point of below 40° C., 50° C. or 60° C. determined,        for example, by DSC measurement;    -   (c) a flame retardant filler, which preferably is a hydrated        metal-based filler;    -   (d) 0.1-3.0 wt.-% of an antioxidant; and    -   (e) 0.5-2.5 wt.-% of a coupling agent composition

Conjunction devices comprising elements surrounded by a polymercomposition have to fulfill various demands. First of all, it must bepossible to prepare the devices in an economic manner by using standardmanufacturing devices such as extruders. Therefore, the polymercomposition has to be suitable for being applied to and/or onto theinner elements by way of HFFR (Halogen-Free Flame Retardant) extrusion.

During use, conjunction devices are subjected to bending movements andpull force conditions for a very high number of times such as severalhundreds of bending movements and pull force conditions over thelifetime of said devices. Under such extreme conditions, polymers usedas the material for surrounding the structure of the conjunction devicescan break. In order to avoid breaking of the polymer coat, theflexibility of the polymers is increased. However, several otherproperties also have to be fulfilled by the conjunction devices, andincreasing the flexibility of the polymers can result in deteriorationof other properties (cf. experimental section hereinafter). For example,flexibility of the polymer can be increased by reducing the content offlame retardant filler, resulting in reduced flame retardancy. At thesame time, the degree of indentation in the hot pressure test mayincrease, since the increased flexibility reduces the dimensionalstability.

Further difficulties arise if halogen-free flame retardants are used.Avoiding halogens is desirable, because halogenated flame retardantshave many drawbacks, since they partially decompose during processing ofthe polymer, or if the polymer catches fire during use, giving rise tohalogenated fumes that are toxic and corrosive. However, to impartsufficient flame retardancy, high levels of halogen-free flameretardants/fillers have to be used. Such high levels of filler lead to areduction in processability and in mechanical and elastic properties ofthe resulting polymer composition, in particular as regards impactresistance, elongation, flexibility and stress at break.

The various parameters which have to be met by conjunction devices arepreset by the industry on the basis of various standards, which arementioned herein.

For example, the conjunction devices have to comply with the hotpressure test in order to have good mechanical resistance to highertemperatures, i.e., have to provide correct values under the respectivetest conditions (<50%, ENSO 363) in accordance with IEC 60811-508 (4 hrs@80° C.). Although the single/pure components of polymer composition,such as the polyolefin elastomers, may fail the hot pressure test whentested on their own, the extruded multicomponent polymer composition maypass the hot pressure test. Accordingly, in order to meet the hotpressure test, it is not possible to simply select starting materialswhich pass the hot pressure test, expecting that this property will beretained in the multicomponent extruded polymer composition.

The main challenge, however, is the alternate bending test or also knownfrom persons skilled in the art as “Two pulley flexing test” (EN 50396)which is cost and time consuming. A test specimen has to be subjected to30000 test cycles. For performing the test, a fully industriallyproduced prototype is needed. Therefore, it is rather a validation test,after the final development, but not a test which can be used foroptimizing the polymer composition.

The most important parameters which define the suitability and qualityof a conjunction device are: Flame retardancy which complies with thetest for vertical flame propagation according to EN 60332-1-2 (which iscost and time consuming because the test is executed on the finalproduct as well as on the polymer composition), good resistance topressure at high temperatures (mechanical protection) (hot pressuretest, ISO 6722), high elongation at break (IEC 60811-501), gooddimensional stability (hot pressure test, ISO 6722), high strength atbreak (IEC 60811-501), and high flexibility (alternate bending test, EN50396). Other properties which may be good relate to the waviness, lowfriction, resistance to scratches, and stripping force.

Since an infinite number of polymers, monomers and polymer additives areavailable, it is impossible to randomly prepare and test polymersregarding their parameters. Furthermore, as explained above, it is notpossible to optimize one parameter after another, since changing thepolymer composition influences all parameters positively or negativelyat the same time. In other words, it is difficult to find the “sweetspot”, where all parameters are balanced at an acceptable or best level.It is not even possible to determine in advance, whether a particularcombination of starting materials is suitable for providing an extrudedpolymer composition which meets all industrial standards.

Therefore, it has been unexpectedly found that the polymer compositionsof the present invention represent such a “sweet spot”, where all oressentially all above industrial requirements may be complied with. Thepolymer compositions are characterized by a combination of a specificlinear very low density polyethylene (VLDPE) composition and a specificultra-low density random ethylene-octene copolymer(polyolefin-elastomer) at high levels of HFFR filler. The “sweet spot”is defined by the specific combination of materials and the narrowlydefined window for the amounts thereof. As demonstrated by the examplesherein, working outside this “sweet spot” results in deterioration ofone or more parameters.

As seems to be suggested by the examples, a high elongation at break andgood performance in the alternate bending test can even be obtained whenusing very high levels of HFFR fillers. The use of a randomethylene-octene copolymer seems to be superior to the use of a blockoctene copolymer regarding elongation at break. A comparison betweencompositions 3 and 4 (cf. examples 3 and 4) seems to suggest that theuse of a propylene-based elastomer does not provide a very highelongation as is obtained when using a random ethylene-octene copolymeras the polyolefin-elastomer. Likewise, the use of an ethylene vinylacetate copolymer instead of the specific VLDPEs does not allowproviding a high elongation at break and does not allow passing the hotpressure test (cf. example 5). Example 6 seems to suggest that the useof a random ethylene-octene copolymer is superior to the use of anα-olefin copolymer regarding elongation at break. Example 7 seems tosuggest that a low amount of VLDPEs in combination with an amorphouspropylene-ethylene copolymer, in addition to a block octene copolymer asthe polyolefin-elastomer, does not allow passing the hot pressure test.Example 8 seems to suggest that the use of a higher amount of POE butlower amount of VLPDEs does not allow passing the hot pressure test.

Thus, the invention relates to conjunction devices and polymercompositions for preparing same as defined in the claims, wherein saidconjunction devices and polymer compositions allow complying with all oressentially all industrial standards which are referred to herein.

DETAILED DESCRIPTION

The invention relates to the following items:

1. Polymer composition comprising at least the following components:

-   -   (a) 24-32 wt.-% of a linear very low density polyethylene        (VLDPE) composition having a density in the range from 0.85        g/cm³ to 0.95 g/cm³, as measured according to ISO 1183;    -   (b) 10-17 wt.-% of a polyolefin-elastomer, which is an ultra-low        density random ethylene-octene copolymer having    -   a glass transition temperature of −50° C., and/or    -   a melting point of below 40° C., 50° C. or 60° C. determined,        for example, by DSC measurement;    -   (c) a flame retardant filler, which preferably is a hydrated        metal-based filler;    -   (d) 0.1-3.0 wt.-% of an antioxidant; and    -   (e) 0.5-2.5 wt.-% of a coupling agent composition

2. The polymer composition according to item 1, wherein the linear verylow density polyethylene (VLDPE) composition has a density in the rangefrom 0.87 g/cm³ to 0.91 g/cm³, as measured according to ISO 1183, and/orhaving a melting point of above 110° C., e.g., as measured by adifferential scanning calorimetry (DSC) measurement.

3. The polymer composition according to item 1 or 2, wherein thepolyolefin-elastomer consists of one or more olefin elastomer(s), whichpreferably is/are (an) ultra-low density random ethylene-octenecopolymer(s) having a glass transition temperature of below −45° C. asdetermined in the polymer composition or in pure form, wherein thedetermination of the melting point will be provided, e.g., from the DSCmeasurement, and/or a melting point of below 39° C. as determined in thepolymer composition or in pure form, wherein the determination of themelting point will be provided on basis of, e.g., the DSC measurement,wherein, by way of example, Engage° 8842 of Dow has a very low meltingpoint of 38° C.

4. The polymer composition according to any preceding item, wherein theflame retardant filler is present in an amount of 56-65 wt.-%,preferably 55-58%, and preferably is aluminum hydroxide or magnesiumhydroxide.

5. The polymer composition according to any preceding item, having anelongation at break in the range from 300% to 500%, preferably 350% to450%, or 350% to 500%, as measured by IEC 60811-501, preferably measuredby using a conjunction device prepared from said polymer composition, inparticular a conjunction device in the form of a hollow cable withconductors removed according to EN 50363-8.

6. The polymer composition according to any preceding item, having astrength at break in the range from 7.5 MPa to 15.0 MPa, 7.5 MPa to 10.0MPa, or 7.5 MPa to 9.0 MPa, preferably before ageing, as measured by IEC60811-501 and as required by DIN EN 50363-8, preferably measured byusing a conjunction device prepared from said polymer composition, inparticular a conjunction device in the form of a hollow cable withconductors removed according to EN 50363-8. During ageing, the samplesare placed into an oven for 7 days at 80° C., then put into a desiccatorand then tested. The deviation in elongation and tensile strength ispreferably not bigger than ±20%. Unless otherwise stated, all valuesreferred to herein are measured without ageing.

7. The polymer composition according to any preceding item, wherein thelinear very low density polyethylene composition comprises a mixture oftwo different types of linear very low density polyethylenecompositions, preferably a mixture of 20-26 wt.-% of a firstcomposition, preferably having a density in the range from 0.87 g/cm³ to0.92 g/cm³, preferably of about 0.9 g/cm³, as measured according to ISO1183, and 1-7 wt.-% of a second composition, preferably having a densityin the range from 0.87 g/cm³ to 0.92 g/cm³, preferably of about 0.9g/cm³, as measured according to ISO 1183. Preferably, the VLDPE, whichis present in a higher amount, has a higher melt flow rate compared withthe other VLDPE. Preferably, the VLDPE being present in an amount of 1-7wt.-% has a melt flow index of 2-5, as determined according to ASTM1238(190° C./2.16 kg; g/10 min), while the VLDPE being present in an amountof 20-26 wt.-% has a melt flow index of 8-15 as determined according toASTM1238 (190° C./2.16 kg; g/10′).

8. The polymer composition according to any preceding item, wherein thelinear very low density polyethylene composition has a density in therange from 0.87 g/cm³ to 0.92 g/cm³, preferably in the range from 0.87g/cm³ to 0.90 g/cm³, as measured according to ISO1183.

9. The polymer composition according to any preceding item, wherein thepolyolefin-elastomer has a density in the range from 0.81 g/cm³ to 0.90g/cm³, preferably of about 0.86 g/cm³, as measured according to ASTMD792.

10. The polymer composition according to any preceding item, wherein thepolyolefin-elastomer (composition) has an elongation at break of atleast 900%, further preferred at least 1100%, most preferably about1200%, as measured by ASTMD638.

11. The polymer composition according to any preceding item, wherein thepolyolefin-elastomer has a value of ShoreD hardness of less than 21, asmeasured by ASTM D2240 (compression molded sample, wherein a sample ofthe polyolefin-elastomer is molded into a plate).

12. The polymer composition according to any preceding item, wherein thepolymer composition is applied by hot-melt extrusion at a temperature inthe range from 100° C. to 180° C., preferably 100-170° C.

13. The polymer composition according to any preceding item, wherein theflame retardant filler is fine precipitated hydrated metal-based filler,e.g., aluminum hydroxide or magnesium hydroxide, preferably having atleast 99.0% purity. One example of such filler is Martinal® OL-104 LEO.

14. The polymer composition according to any preceding item, wherein thecoupling agent composition is a mixture of vinyltriethoxysilane and1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

15. The polymer composition according to any preceding item, wherein theantioxidant is a phenolic antioxidant, preferablytetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane.

16. The polymer composition according to any preceding item, which doesnot contain a plasticizer.

17. The polymer composition according to any preceding item, wherein thepolymer composition does not contain a high density polyethylenehomopolymer having a density of 0.94 g/cm³ or higher, preferably notcontaining a high density polyethylene homopolymer having a density of0.92 g/cm³ or higher.

18. The polymer composition according to any preceding item, which doesnot contain a polysiloxane.

19. The polymer composition according to any preceding item, wherein theglass transition temperature of the polyolefin-elastomer/ultra-lowdensity random ethylene-octene copolymer is −58° C.

20. The polymer composition according to any preceding item, which isnot UV crosslinked.

21. The polymer composition according to any preceding item, having anMFI of at least 9 g/10 min, as measured according to EN ISO 1133 underthe conditions at 150° C. and the load of 21.6 kg.

22. The polymer composition according to any preceding item, wherein thedensity of the polyolefin-elastomer/ultra-low density randomethylene-octene copolymer is in the range from 0.80 g/cm³ to 0.90 g/cm³,as measured according to ISO 1183.

23. The polymer composition according to any preceding item, having avalue of ShoreD hardness of 32-38.

24. The polymer composition according to any preceding item, wherein thelinear very low density polyethylene (VLDPE) composition having amelting point above 110° C., preferably has a melting point which isbelow 120° C. measured and/or determined by the method of DSCmeasurement.

25. The polymer composition according to any preceding item, wherein thelinear very low density polyethylene (VLDPE) composition has a Vicattemperature (Vicat softening temperature) of above 50° C., for example,measured according to the ASTM D1525 method.

The polymer composition may be used in a conjunction device comprisingone or more elements including a static/moving charge/current (orelectric charge) medium or communication medium, wherein the polymercomposition surrounds these element(s).

The conjunction device may comprise from 1 to 10 elements includingstatic/moving current media or communication media, e.g., made of metal,each surrounded by a polymer layer, each element having diameters of upto 4.0 mm, such as diameters of 0.5 to 4.0 mm, and preferably havingfrom 2 to 5 elements. The polymer composition may surround the elementsto provide a sheath for mechanical protection of the elements.

In the context of the present invention, the “conjunction device” can bean elongated device for conjunction and/or connection of two devices fortransferring electrical charges and/or information such as for powertransmission or telecommunications. For example, the “conjunctiondevice” can be a cable. In such a “conjunction device”, the elements(which are surrounded by the polymer composition) can each include anelectric conductor as the static/moving current medium or communicationmedium. The electric conductor is optionally itself surrounded by ashielding or sheathing, in particular a polymer composition/coating,thereby forming the element. The electrical conductor can be a wire,preferably comprising or consisting of one or more, e.g., 52, metalstrands (e.g., copper strands), wherein the wire is optionally itselfsurrounded by a shielding or sheathing, thereby forming the element. Thecable can, e.g., be used as low voltage cable such as for use in vacuumcleaner applications.

In the context of the present invention, the weight percentagesindicated for the components of the polymer composition are indicated asweight percentages based on the total weight of the polymer composition.

Linear very low density polyethylenes (VLDPEs) as used herein arehomopolymers.

In the context of the present invention, the “linear very low densitypolyethylene (VLDPE)”, “ultra-low density random ethylene-octenecopolymer (polyolefin-elastomer)” and any other polymer component can beused in the form of commercially available products. Since theseproducts may contain minor amounts of additives (e.g., antioxidants), inaddition to, e.g., pure polyethylene or ethylene-octene copolymer, theaforementioned terms, e.g., “linear very low density polyethylene(VLDPE)”, and “ultra-low density random ethylene-octene copolymer(polyolefin-elastomer)”, encompass compositions comprising such minoramounts of additives, e.g., amounts of additives of below 1.0 wt.-% orbelow 0.5 wt.-%. It can reasonably be expected that such minor amountsof additives do not have a significant impact on the final properties ofthe polymer composition.

In the context of the present invention, the parameters defined herein,in particular in the claims, can either be determined by testing theconjunction device, the polymer composition, or the single/purecomponents of the polymer composition. A person skilled in the art candetermine the most feasible approach. For example, if the density of aVLDPE, which is present in the polymer composition of a conjunctiondevice, is not known, the VLDPE may be extracted from the polymercomposition and analyzed. If the glass transition temperature or meltingpoint of a polyolefin-elastomer, which is present in the polymercomposition of a conjunction device, is unknown, these parameters can bedetermined via DSC methods on the polymer composition.

As disclosed above, the invention relates to polymer compositionscomprising components (a)-(e). These polymer compositions are suitablefor preparing a conjunction device comprising:

-   -   (i) one or more elements including a static/moving current        medium or communication medium; and    -   (ii) said polymer composition of the invention which surrounds        the element(s). The conjunction device can be configured and can        be used for connecting two devices for exchange of        charges/information between the devices.

Component (i) is one or more elements including a static/moving chargemedium or communication medium. The elements can have an elongated formwith two ends in order to, e.g., each have a length of up to severalkilometers. The elongated elements are aligned and are surrounded bycomponent (ii). Furthermore, the static/moving current medium orcommunication medium of each of the elements can itself be surrounded bya coat, e.g., polymer coat/composition, which provides a shielding orsheathing. The one or more optionally surrounded static/moving currentmedia or communication media together form component (i). Component (ii)mechanically protects component (i). During use of the conjunctiondevice, components (i) and (ii) may be subjected to many bendingmovements and pull force. As explained above, the conjunction devicesdisclosed herein may have sufficient flexibility to avoid breakingthereof even after a very long period of use (determined by thealternate bending test).

The polymer composition of the invention is a halogen-free polymercomposition/component surrounding the element(s), i.e., component (i).It is not excluded, but less preferred, that there are additionalcoatings which either surround component (ii) or which are betweencomponents (i) and (ii).

The polymer composition is obtainable or obtained by compounding andextrusion, preferably HFFR compounding, of all respective components.

Component (a): 24-32 wt.-%, preferably 26-30 wt.-%, of a linear very lowdensity polyethylene (VLDPE) composition having a density in the rangefrom 0.85 g/cm³ to 0.95 g/cm³, as measured according to ISO 1183, andpreferably having a melting point of above 110° C. as determined bydifferential scanning calorimetry. Such commercially availablepolyethylenes are, e.g., Clearflex® MQF0 of Versalis and Clearflex® CLD0of Polimeri Europa. One embodiment is 22.0-25.5% Clearflex® MQF0, 3-5%Clearflex® CLD0 and 12.5-14.0% Engage 8842 with, e.g., 56-57%, e.g.,56%, or 57% flame retardant filler, and optional components as definedin items 1 and 2 adding up to 100% herein.

The linear very low density polyethylene (VLDPE) composition having amelting point above 110° C., e.g., related to the differential scanningcalorimetry (DSC) measurement, preferably has a melting point which isbelow 120° C. as, e.g., also determined by differential scanningcalorimetry (DSC).

The linear very low density polyethylene (VLDPE) composition can have aVicat temperature (Vicat softening temperature) of above 50° C. forexample, measured according to the ASTM D1525 method.

Component (b): 10-17 wt.-%, preferably 10-16 wt.-%, or 12-14 wt.-% of apolyolefin-elastomer or one or more polyolefin-elastomers, which is anultra-low density random ethylene-octane copolymer having a glasstransition temperature of below −50° C. as determined by differentialscanning calorimetry, and a melting point of below 60° C. or below 50°C., preferably below 40° C., as determined by differential scanningcalorimetry. Such commercially available polyolefin-elastomers areEngage® 8842, Engage® 8180, Engage® 8130, and Engage® 8150 of Dow.

Component (c): flame retardant filler, preferably present in an amountof 55-65 wt.-%, preferably 55-58%, which preferably is a mineralhydroxide/hydrated mineral. Preferably, the polymer composition does notcontain further polyethylene components and/or furtherpolyolefin-elastomers.

Compounding of the polymer composition can be performed by mixing thecomponents in a molten state. A device which can suitably be used forextrusion in this context is an extruder, e.g., a twin screw extruder,single screw kneading extruder. Compounding can be performed in anIntermixer.

The flame retardant filler or fillers used in the present invention arehalogen free. According to the present invention, mineral hydroxides,i.e., mineral fillers which are hydrated oxides can be used. Forexample, aluminum or magnesium hydroxides, can be used. When exposed tohigh temperatures, the mineral fillers decompose through endothermicreaction and release large quantities of water, so as to stop the flamepropagation. The flame retardant filler preferably is aluminum hydroxideor magnesium hydroxide, preferably fine precipitated aluminum hydroxideof about 99.4% purity. One example of such filler is Martinal® OL-104LEO of Albemarle.

Preferably, the flame retardant filler is used in an amount of 57-65wt.-%, or 55-58%. In one embodiment, a combination of Clearflex MQF0,Clearflex CLD0 and Engage® 8842 is used.

The polymer composition further comprises (d): 0.1-3.0 wt.-% of anantioxidant; and (e): 0.5-2.5 wt.-% of a coupling agent composition.

Preferably, the polymer composition has

-   -   (aa) an elongation at break in the range from 300% to 500%,        preferably 350% to 500%, or 350% to 450%, as measured by IEC        60811-501, preferably before ageing and preferably by using the        conjunction device without the inner elements, in particular a        conjunction device in the form of a hollow cable with conductors        removed according to EN 50363-8, and/or,    -   (bb) a strength at break in the range from 7.5 MPa to 15.0 MPa,        or 8 N/mm² to 15 N/mm², as measured by IEC 60811-501, preferably        before ageing and preferably by using the conjunction device        without the inner elements.

The linear very low density polyethylene composition can comprises amixture of two different types of linear very low density polyethylenecompositions, preferably a mixture of 20-26 wt.-% of a first compositionhaving a density in the range from 0.85 g/cm³ to 0.95 g/cm³, preferablyof about 0.90 g/cm³, as measured according to ISO 1183, and 1-7 wt.-% ofa second composition having a density in the range from 0.85 g/cm³ to0.95 g/cm³, preferably of about 0.90 g/cm³, as measured according to ISO1183.

The linear very low density polyethylene composition can have a densityin the range from 0.85 g/cm³ to 0.92 g/cm³, preferably in the range from0.85 g/cm³ to 0.90 g/cm³, as measured according to ISO 1183.

The polyolefin-elastomer can have a density in the range from 0.80 g/cm³to 0.90 g/cm³, preferably of about 0.86 g/cm³, as measured according toASTM D792.

The polyolefin-elastomer composition used for preparing the polymercomposition can have an elongation at break of at least 1000%, furtherpreferred at least 1100%, most preferably about 1200%, as measured byASTMD638.

The polyolefin-elastomer can have a value of ShoreD hardness of lessthan 20, as measured by ASTM D2240 (compression molded sample).

The polymer composition is applied by hot-melt extrusion at atemperature in the range from 100° C. up to 175° C., in a preferredembodiment of the invention in a range from 100° C. to 170° C.

The coupling agent composition can be a mixture of vinyltriethoxysilane(Dynasilan° VTEO of Evonik) and1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane (Trigonox 29-C50 ofAkzoNobel).

The antioxidant can be a phenolic antioxidant, preferablytetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (e.g., Irganox 1010 of BASF).

The conjunction device can comprise from, e.g., 1 to 8 elements, eachpreferably having a diameter of up to 4.0 mm, such as diameters from 0.5to 4.0 mm, and preferably having from 2 to 5 elements. Preferably, theelements are elongated and/or stranded. The static/moving current mediumor communication medium of the elongated elements is preferablysurrounded by a polymer composition. The static/moving current media orcommunication media can be wires, such as copper wires, and canoptionally be surrounded by an insulation/polymer composition. Thecross-section of each element without insulation, i.e. the cross-sectionof each of the static/moving current medium or communication medium, canfor example be from 0.5 to 4.0 mm². The elements, comprising thestatic/moving current medium or communication medium which aresurrounded by a polymer composition, are brought in contact with and thepolymer composition (ii) is then applied to the elements in an extrusionprocess. Preferably, the outer diameter of the conjunction device ismore than 6.2 mm, preferably 8.2 mm or more, such as 7.5 to 9 mm.Preferably, the conjunction device has a diameter so that it can include3 elements, each comprising a static/moving current medium orcommunication medium, e.g. an electrical conductor, which is surroundedby a polymer composition and each having a cross-section, including thepolymer composition, of 0.75 mm² or more, wherein the diameter of all 3elements together is about 6 mm. In one embodiment, the polymercomposition does not contain a plasticizer.

The polymer composition preferably does not contain a high densitypolyethylene homopolymer having a density of 0.94 g/cm³ or higher,preferably not containing a high density polyethylene homopolymer havinga density of 0.92 g/cm³ or higher.

The polymer composition preferably does not contain a polysiloxane. Thepolymer composition preferably does not contain a maleic anhydridegrafted polymer.

The polymer composition surrounds the elements to provide insulation formechanical protection of the elements as well as protection of peoplefrom contact with electrical current. The polymer compositionsurrounding elements is preferably provided in the form of a sheath. Forexample, the polymer composition coating the elements has a tubularshape.

The glass transition temperature of the polyolefin-elastomer/ultra-lowdensity random ethylene-octene copolymer preferably is −58° C. In oneembodiment, the density of the polyolefin-elastomer/ ultra-low densityrandom ethylene-octene copolymer is in the range from 0.80 g/cm³ to 0.90g/cm³, as measured according to ISO 1183.

The polymer composition is preferably not UV crosslinked.

In one embodiment, the conjunction device has an MFI of at least 9 g/10min, as measured according to EN ISO 1133 under the conditions at 150°C. and the load of 21.6 kg.

In one embodiment, the polymer composition has a ShoreD hardness of lessthan 32-38, as measured by ASTM D2240 (compression molded sample). Theaforementioned properties can, e.g., be determined by using the polymercomposition in the form of a hollow cable with conductors removedaccording to EN 50363-8.

The process for preparing a conjunction device may comprise the stepsof:

-   -   (i) providing one or more elements including a static/moving        current medium or communication medium;    -   (ii) compounding the components of the polymeric composition and        then extrusion of the polymeric composition as described herein        onto the one or more elements; and    -   (iii) obtaining said conjunction device.

The step of compounding and extrusion is performed in two steps and indifferent devices:

-   -   (iia) a compounding step, e.g. in a mixer, and afterwards (iib)        the extrusion step in an extruder.

EXAMPLES

The following examples describe the present invention in detail, but arenot to be construed to be in any way limiting for the present invention.

VLDPE1 (Clearflex MQF0 of eni/versalis): Is a linear very low densitypolyethylene (VLDPE) having a density in the range from 0.85 g/cm³ to0.93 g/cm³, as measured according to ISO 1183, and having a meltingpoint of above 110° C. It has a melt flow index of 8-15 as determinedaccording to ASTM1238 (190° C./2.16 kg; g/10′).

VLDPE2 (Clearflex CLD0 of Polimeri Europa, Eni): Is a linear very lowdensity polyethylene (VLDPE) having a density in the range from 0.85g/cm³ to 0.93 g/cm³, as measured according to ISO 1183, and having amelting point of above 110° C. It has a melt flow index of 2-5 asdetermined according to ASTM1238 (190° C./2.16 kg; g/10 min).

POE1 (Engage 8842, random octene copolymer): Is an ultra-low densityrandom ethylene-octene copolymer having a glass transition temperatureof below −50° C. and having a melting point of below 40° C.

POE2 (Exact8203 of ExxonMobil, block octene copolymer) : Is an ultra-lowdensity random ethylene-octene copolymer having a glass transitiontemperature of below −50° C. and having a melting point of below 40° C.The polymer has an MFI of 3.0 g/10 min, a density of 0.888 g/ccm, amelting point of 72° C., a glass transition temperature of <−75° C. anda Vicat softening point of 51° C.

POE3 (Engage HM7487 of the Dow Chemical Company, random octenecopolymer): Is an ultra-low density random ethylene-octene copolymerhaving a glass transition temperature of below −50° C. and having amelting point of below 40° C. The polymer has an MFI of <0.5 g/10 min, adensity of 0.862 g/ccm, a melting point of 37° C., a and a glasstransition temperature of <−57° C.

The test method and sample preparation for the measurement of theelongation is performed as with a sheathing material described in EN50363-8, wherein the conjunction device without the one or more elementsis subjected to the measurement.

The compositions in the examples were extruded into cables using a HFFRextruder, with HFFR extrusion head and HFFR screw, at a temperature inthe range from 100° C. up to 175° C. The process conditions can bechosen by a person skilled in the art.

Example—1 Composition 1

Composition 1 is characterized by a combination of a VLDPE (VLDPE1), inan amount of 25 wt.-% and a block octene copolymer (POE2) in an amountof 10 wt.-%. At a high filler level of ATH (aluminum hydroxide) of 63%,the elongation was below 300%.

Composition 1 25% VLDPE1 10% POE2 63% ATH 1% Antioxidant 1% Couplingagent

The measured elongation was <300%. Composition 1 passed the alternatebending test, EN 50396.

Example—2 Composition 2

Composition 2 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 32 wt.-%. The two VLDPEs areused in combination with a block octene copolymer (POE2). An additionallow level of ATH (aluminum hydroxide) of 58% gives a high elongation.

Composition 2 24% VLDPE1 8% VLDPE2 8% POE2 58% ATH 1% Antioxidant 1%Coupling agent

The measured elongation was >300%. Reducing the ATH level from 63% to58% reduces the flame retardancy.

Example—3 Composition 3

Composition 3 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 32 wt.-%. The two VLDPEs areused in combination with a random octene copolymer (POE3). Even at ahigh filler level of ATH (aluminum hydroxide) of 58%, a very highelongation was obtained.

Composition 3 24% VLDPE1 8% VLDPE2 8% POE3 58% ATH 1% Antioxidant 1%Coupling agent

The measured elongation was >400%. A comparison between Compositions 2and 3 seems to confirm the concept underlying the present invention.That is, the specific combination and amounts of components provides thedesired elongation.

Example—4 Composition 4 (Comparative Example)

Composition 4 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 32 wt.-%. The two VLDPEs areused in combination with a propylene-based elastomer.

Composition 4 24% VLDPE1 8% VLDPE2 8% Propylene-based elastomer(copolymer) 58% ATH 1% Antioxidant 1% Coupling agent

The measured elongation was <300%. The measured tensile strength was<7.5 MPa. A comparison between Compositions 3 and 4 seems to suggestthat the use of a propylene-based elastomer does not provide a very highelongation.

Example—5 Composition 5 (Comparative Example)

Composition 5 is characterized by a combination of EVA (ethylene vinylacetate) in an amount of 16 wt.-%. The EVA is used in combination with ablock octene copolymer (POE2).

Composition 5 16% EVA 15% POE2 63% ATH 1% Antioxidant 5% Coupling agentMAH-PE

The measured elongation was <300%. The composition failed the hotpressure test (80° C.>50%). A comparison between the above compositionsseems to suggest that the use of EVA does not provide a very highelongation and dimensional stability. Additionally, another couplingagent does not improve the properties.

Example—6 Composition 6 (Comparative Example)

Composition 6 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 28 wt.-%. The two VLDPEs areused in combination with an α-olefin copolymer.

Composition 6 21% VLDPE1 7% VLDPE2 7% α-olefin copolymer (Vestoplast750) 63% ATH 1% Antioxidant 1% Coupling agent

The measured elongation was <300%. A comparison between the abovecompositions seems to suggest that the use of a random ethylene-octenecopolymer is superior to the use of an α-olefin copolymer regardingelongation at break.

Composition 7 (Comparative Example)

Composition 7 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 20 wt.-%. The two VLDPEs areused in combination with an amorphous propylene-ethylene copolymer andPOE2.

Composition 7 16% VLDPE1 4% VLDPE2 10% POE2 5% Amorphous propylene-ethylene copolymer, Eastoflex 1060PL 63% ATH 1% Antioxidant 1% Couplingagent

The measured elongation was >300%. The composition failed the hotpressure test (hot pressure test 80° C.>50%). The experiment seems toshow how changing the polymer compositions results in deterioration ofthe properties.

Composition 8

Composition 8 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 18 wt.-%. The two VLDPEs areused in combination with a random octene copolymer (POE3) in an amountof 17%.

Composition 8 14% VLDPE1 4% VLDPE2 17% POE3 63% ATH 1% Antioxidant 1%Coupling agent

The measured elongation was >400%. The composition failed the hotpressure test (80° C.>50%). The example seems to suggest that the amountof POE was too high for mechanical stability at high temperatures butgood for elongation at break at room temperature.

Composition 9

Composition 9 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 23 wt.-%. The two VLDPEs areused in combination with a random octene copolymer in an amount of 13%.

Composition 9 20% VLDPE1 3% VLDPE2 13% POE1 62% ATH 1% Antioxidant 1%Coupling agent

The measured elongation was >400%. The flexibility test was achievedwith a test conjunction device.

Composition 10

Composition 10 is characterized by a combination of two VLDPEs, i.e.,VLDPE1 and VLDPE2, in a total amount of 30 wt.-%. The two VLDPEs areused in combination with a random octene copolymer (POE1) in an amountof 10%.

Composition 10 20% VLDPE1 10% VLDPE2 10% POE1 58% ATH 1% Antioxidant 1%Coupling agent

The measured elongation was >430%. With this formulation, theflexibility test can be achieved with a conjunction device with threeinner elements, each having a cross-section of 1.5 mm².

CITED LITERATURE

-   EP1102282 A1-   DE3633056 A1-   WO 2010015876 A1-   WO 2013030795 A1-   WO 2002026879 A1-   WO 2007032573 A1-   WO 2008014597 A1 and-   WO 2010024602 A2

1. Polymer composition comprising at least the following components: (a)24-32 wt.-% of a linear very low density polyethylene (VLDPE)composition having a density in the range from 0.85 g/cm³ to 0.95 g/cm³,as measured according to ISO 1183; (b) 10-17 wt.-% of apolyolefin-elastomer, which is an ultra-low density randomethylene-octene copolymer having a glass transition temperature of −50°C.; (c) a flame retardant filler; (d) 0.1-3.0 wt.-% of an antioxidant;and (e) 0.5-2.5 wt.-% of a coupling agent composition.
 2. The polymercomposition according to claim 1, wherein the linear very low densitypolyethylene (VLDPE) composition has a density in the range from 0.87g/cm³ to 0.91 g/cm³, as measured according to ISO
 1183. 3. The polymercomposition according to claim 1, wherein the flame retardant filler ispresent in an amount of 55-65 wt.-%.
 4. The polymer compositionaccording to claim 1 having an elongation at break in the range from300% to 500%, as measured by IEC 60811-501.
 5. The polymer compositionaccording to claim 1 having a strength at break in the range from 8 MPato 10 MPa, as measured by IEC 60811-501.
 6. The polymer compositionaccording to claim 1, wherein the linear very low density polyethylenecomposition comprises a mixture of two different types of linear verylow density polyethylene compositions.
 7. The polymer compositionaccording to claim 1, wherein the linear very low density polyethylenecomposition has a density in the range from 0.87 g/cm³ to 0.92 g/cm³, asmeasured according to IS01183.
 8. The polymer composition according toclaim 1, wherein the polyolefin-elastomer has a density in the rangefrom 0.81 g/cm³ to 0.90 g/cm³, as measured according to ASTM D792. 9.The polymer composition according to claim 1, wherein thepolyolefin-elastomer has a value of ShoreD hardness of less than 21, asmeasured by ASTM D2240.
 10. The polymer composition according to claim1, wherein the flame retardant filler is fine precipitated hydratedmetal-based filler.
 11. The polymer composition according to claim 1,wherein the polymer composition does not contain a high densitypolyethylene homopolymer having a density of 0.94 g/cm³ or higher. 12.The polymer composition according to claim 1, wherein the glasstransition temperature of the polyolefin-elastomer/ultra-low densityrandom ethylene-octene copolymer is −58° C.
 13. The polymer compositionaccording to claim 1, wherein the density of thepolyolefin-elastomer/ultra-low density random ethylene-octene copolymeris in the range from 0.80 g/cm³ to 0.90 g/cm³, as measured according toISO
 1183. 14. The polymer composition according to claim 1, wherein thelinear very low density polyethylene (VLDPE) composition having amelting point above 110° C.
 15. The polymer composition according toclaim 1, wherein the linear very low density polyethylene (VLDPE)composition has a Vicat softening temperature of above 50° C.
 16. Use ofthe polymer composition of claim 1 for the preparation of conjunctiondevices.
 17. The polymer composition according to claim 1, wherein theflame retardant filler is a hydrated metal-based filler.
 18. The polymercomposition according to claim 1, wherein the flame retardant filler ispresent in an amount of 55-65 wt.-% and is aluminum hydroxide.
 19. Thepolymer composition according to claim 14, wherein the linear very lowdensity polyethylene (VLDPE) composition has a melting point which isbelow 120° C.
 20. The polymer composition according to claim 1, whereinthe linear very low density polyethylene (VLDPE) composition has adensity in the range from 0.87 g/cm³ to 0.91 g/cm³, as measuredaccording to ISO 1183, and has a melting point of above 110° C.,measured by differential scanning calorimetry (DSC).
 21. Polymercomposition comprising at least the following components: (a) 24-32wt.-% of a linear very low density polyethylene (VLDPE) compositionhaving a density in the range from 0.85 g/cm³ to 0.95 g/cm³, as measuredaccording to ISO 1183; (b) 10-17 wt.-% of a polyolefin-elastomer, whichis an ultra-low density random ethylene-octene copolymer having amelting point of below 40° C., as determined by DSC measurement: (c) aflame retardant filler; (d) 0.1-3.0 wt.-% of an antioxidant; and (e)0.5-2.5 wt.-% of a coupling agent composition.